This invention relates generally to an improved manhole cover and related method of installation, particularly for use in lockably closing a manhole or other access opening formed in an overhead soffit structure to restrict access to an otherwise enclosed overhead cell or chamber formed, e.g., within a concrete overpass or bridge structure of a light rail or highway transportation system or the like. More specifically, the locking cover of the present invention is designed for securely closing the soffit manhole in a manner that substantially prevents unauthorized access to the overhead cell or chamber by unauthorized persons.
Modern overhead structures such as concrete overpasses and bridges used in rail and highway transportation systems often incorporate internal, substantially enclosed cells or chambers which are accessed from below through one or more hatch or access openings such as circular manholes formed in an overhead soffit structure. Such enclosed cells or chambers may be vacant, but sometimes house equipment or facilities such as components of a public utility system, e.g., water mains, sewer drain pipes, and electrical wiring and related conduits.
In the past, manhole covers in the form of metal plates have been provided for normally closing such soffit manholes to discourage access to these overhead enclosed cells or chambers by unauthorized persons such as vagrants or vandals. However, such manhole covers have been designed for relatively quick and easy slide-fit installation, and for correspondingly quick and easy slide-out removal for periodic or as-needed access by authorized personnel. Accordingly, such slide-fit manhole covers have provided little or no effective security against slide-out removal by unauthorized persons desiring to use the overhead cells or chambers as living quarters and/or for other nefarious activities including but not limited to damaging the overpass or bridge structure or the equipment and facilities carried thereby. Alternative manhole cover designs such as wedge-fit arrangements have been provided in an effort to discourage unauthorized removal from the access opening, but these too have been susceptible to unauthorized tampering and removal by enterprising individuals.
There exists, therefore, a need for further improvements in and to covers for use in closing soffit manholes, wherein the improved manhole cover is designed for secure, substantially tamper-proof locking to provide a high degree of security by precluding unauthorized access to an otherwise enclosed overhead soffit cell or chamber, and further wherein the locking manhole cover can be unlocked and removed or opened relatively quickly and easily by authorized personnel to accommodate as-needed access. The present invention fulfills these needs and provides further related advantages.